Crystal Plex Algae Control

2.5 out of 5 stars 6 Reviews | 10 Q&A

Crystal Plex Algae Control

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Average Rating

2.5 out of 5 stars Rating: 2.5

6 Reviews | 10 Q&A

Product Overview

Crystal Plex Algae Control is a liquid copper sulfate solution designed to kill and control algae and some aquatic plants including Hydrilla. Crystal Plex Algae Control controls many types of algae like filamentous, chara, and placktonic for a beautiful and safe pond all year long. Crystal Plex Algae Control uses our proprietary stabilizers for long term algae control. Crystal Plex Algae Control is 100% safe for humans, fish, livestock, pets, birds, swimming, consumption, and irrigation. Not for use in Koi or Trout ponds.


Features and Specs

Active Ingredient Copper sulfate pentahydrate 19.8%
Target pests Algae including Filamentous, Chara and Placktonic
For use in Ponds & Lakes, Swimming areas, Golf Courses, Canals, Fish Hatcheries (NOT for Use in Koi or Trout Ponds)
* See label for complete list
Application 1 gallon per 10 gallons of water per acre
* See label for complete application instructions
Pet safe Yes, if used as directed on Label
Formulation Professional Product
NOT FOR SALE TO CT, ME, NY (Restricted To Licensed Applicators Only)
Coverage Area Treats an Acre of Surface Water 1 to 3 ft. Deep
Shipping Weight 10.25 lbs
Manufacturer Sanco Industries (Mfg. Number: 00444)
UPC 768980004448
EPA Registration 83190-1-72838


How do I apply Crystal Plex pond algaecide?

The best way to apply liquid copper sulfate is to do a broadcast spray.  Spray the algae mats with Crystal Plex in sections.  You will only treat 1/3 to 1/2 of your pond at a time to prevent oxygen depletion.  See labeled instructions for application amounts and click here for how tomeasure. The algae will brown up within 48 hours. Copper Sulfate is toxic to Koi, goldfish and trout.

Will Crystal Plex hurt fish or animals?

Crystal Plex liquid copper sulfate and Copper Sulfate granular is safe for livestock, recreation, potable water and not harmful to most fish when used according to label directions. Oxygen depletion is the common cause for a fish kill. There are a few exceptions, Copper sulfate is not meant for small deco ponds and is toxic to Koi, Golfish and Trout.

When do I use Crystal Plex?

Crystal Plex Algae killer, should be applied when you first notice an algae bloom. Typically algae will turn water green, have a slimy film, or thick "horse hair" like mats on the pond. Spot treat with Crystal Plex, liquid copper sulfate as needed waiting 5 to 7 days between treatments. Water tempurature must be 50 degrees or above in order to work effectively.

How often do I need to use Crystal Plex?

Crystal Plex, liquid copper sulfate algae killer, can last in water column for up to 30 days; however, solution can weaken due to rainflow, outflow and evaporation. You may need to add more if you have another algae bloom. Wait a week between applications and only treat a 1/2 or 1/3 of the pond at a time to recover oxygen levels.

How much Crystal Plex should I use?

Properly measure your pond to find the square acreage and average depth. One gallon of Crystal Plex, liquid copper sulfate solution will treat a surface acre 1 to 2 feet deep. Example: 1/2 acre pond 4 feet average depth, mix 1 gallon with 8 to 10 gallons of water. (Water is to help spread the product, not to dilute.) See labeled instructions for all application rates.

Will Crystal Plex still work if it freezes?

Yes, Crystal Plex is still effective in killing algae at the same application rate after it has been frozen.  Freezing affects the residual control for Crystal Plex. Crystal Plex normally has a residual control of over a month.  Frozen Crystal Plex will only have a residual effect in controlling algae for 3-5 days.  When using frozen Crystal Plex be sure to shake well before diluting and spraying algae for control. I recommend using warm water to dilute the frozen Crystal Plex before spraying.

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  • 1 of 5 Stars

    Crystal Plex Algae control

    By Ben on 05/07/2016

    This product didn't work well at all. takes a lot of it to do very little. do not recommend this for algae control.

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    17 of 22 people found this review helpful

  • 5 of 5 Stars

    Worked for me

    By Frank on 06/02/2018

    I used it In my 1/2 acre farm pond on Planktonic algae with In an hour turned dark put a trolling motor in to stir the water pond is beautiful again no algae. Been several weeks since it was used still no regrowth

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    12 of 12 people found this review helpful

  • 1 of 5 Stars

    Chrystal Plex Algae Control

    By Richard on 07/06/2018

    I purchased this product in an attempt to deal with a major algae bloom in an approximately 1-1/2 acre pond behind my residence in southwest Florida. The product use information seemed to be directed at large scale use, perhaps spraying from a boat. Trying to determine the proper amount of concentrate to be diluted in a 2-gallon garden tank sprayer was much too difficult. Spraying near shore from shallow water using the tank sprayer was the only reasonable option. Despite trying different dilutions and different spray densities, I found no detectable change in the sprayed areas of the algae bloom. I additionally tried spraying the diluted product into the plastic tub reservoir for a decorative outdoor fountain and found no decrease in the algae.

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    6 of 6 people found this review helpful

  • 4 of 5 Stars

    Crystal Plex

    By Janelle on 09/27/2020

    I liked the option to have this delivered to our place. The problem is that Fed Ex ruined the first shipment and sent it back. I had to called customer support and ask for my order. The second order arrives damaged again by Fed Ex please consider not using them it was ridiculous how fast he drove down my driveway and then said it was damaged.

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  • 3 of 5 Stars

    Don't freeze

    By Daniel on 04/12/2023

    The notice to keep the product from freezing or it might separate is inside the booklet on the side ,it should be in big print on the outside of the jug.

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    0 of 1 people found this review helpful

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Questions & Answers

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Crystal Plex Algae Control in a pond with 1 gal sprayer. How much product should I dilute in one gal of water?
For one acre, mix 1 gallon of Crystal Plex with 10 gallons of water (12.8 fl oz per gallon of water) and spray directly on the algae mats.

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41 of 54 people found this answer helpful

How long to see results with Crystal Plex Algae Control?

Algae will brown up within 48 hours after treatment of Crystal Plex Algae Control.

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23 of 24 people found this answer helpful

Will the Crystal Plex Algae kill yard grass watered from a treated pool?
The Crystal Plex Algae Control is only designed to control algae in water areas so it should not harm the yard grass. The label states: Do not apply this product in its concentrated form to any crop plants, grass or ornamentals as turf injury could occur. After diluted and sprayed over a pool, and then that pool water used for watering turf injury should not occur. If you are still concerned, you can contact the manufacturer Sanco at 1-888-697-2626.

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9 of 10 people found this answer helpful

Can I use Crystal Plex Algae Control to treat a pool?

According to the manufacturer, Crystal Plex Algae Control is not meant to be used in pools. If you were to do so, the chemical reaction between the two will cause the water in the pool to turn to an ugly red color.

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8 of 11 people found this answer helpful

My fruit trees have brown rot and I see copper recommended to control it. Can Crystal Plex be used them?
No the Crystal Plex Algae Control is not labeled to be used for brown rot or on edibles only in bodies of water for algae.  A better copper product would be the Bonide Liquid Copper Fungicide Concentrate.

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6 of 7 people found this answer helpful

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Crystal Plex Algae Control 2.5 out of 5 stars Rating: 2.5 (6 Reviews / 10 Q&A)

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